The present invention relates to a device for balancing a liquid-based heat-transfer system for a heating system. Such a system is equipped with a boiler or the like for heating a fluid which is sent by way of pump means to heat emitters, such as radiators, by a network of liquid pipes. The device according to the invention also provides thermostatic regulation of a heat emitter.
The present invention also relates to liquid-based circuits using fan convectors. It is as suitable for heating circuits as for cold-water circuits used for the air-conditioning of rooms. The description that follows is essentially given with reference to heating circuits but it also applies to cooling technology using a cold-water circuit or a circuit of some other fluid.
In a heating system, in addition to the boiler, radiators and pipes, there are also regulating means whose function is to correctly distribute the heat-transfer fluid to the heat emitters and ensure that a sufficient flow is sent through each of them. The heating circuit is balanced in order for the system to run properly. This balancing operation involves regulating the various regulating means in such a way as to obtain flowrates which are worked out beforehand for base conditions selected to suit different parts of the system that are kept permanently on. Admittedly, a system will almost never be kept permanently on, but that in no way detracts from the value of balancing a circuit, because if the flowrates are caused to vary in the course of operation, this must be allowed for at the design stage and, if necessary, differential pressure regulators connected in series or in parallel must be provided. This however has to do with regulation rather than balancing of the system.
There are several balancing devices, also known as balancing means, which enable a heating system to be balanced. These means are designed to regulate the distribution of flows to the various branches of the distribution circuits.
First of all, unadjustable balancing means are known. These are apertures, that is to say fixed calibrated orifices whose diameter is determined for each of them from a knowledge of the desired relationship between flowrate and loss of head. The use of this type of means requires a complete and painstaking hydraulic calculation of all the circuits of the system in order to determine the precise characteristics of each aperture. If there is any mistake in the calculation, the only solution is to change the aperture. This solution, though seemingly relatively inexpensive, is therefore very rarely employed.
To avoid having to change the balancing means in the event of a computational error, there exist adjustable balancing means known as for example lockshield valves or thermostatic radiator valves. These means enable the flowrate through a circuit to be regulated and hence balanced on the basis of prior knowledge of the desired relationship between flowrate and loss of head. This requires a complete hydraulic calculation of the entire heating circuit. These adjustable balancing means enable the regulation to be corrected easily in the event of error.
These balancing devices are inexpensive and very widely used by installers. However, they are rarely adjusted as they should be, largely because the calculations are done insufficiently or not at all. Thus fitted with badly adjusted means, the system is therefore unbalanced.
Also known are adjustable balancing means equipped with a device for measuring the flow. These balancing means are generally equipped with a pressure takeoff designed to make a differential pressure measurement. This measurement can be used to determine the fluid flowrate through the balancing means. Using an electronic differential manometer with a microprocessor, measurements of differential pressure and of flowrate can be taken quickly and easily.
For the installer, this type of balancing means has a very appreciable advantage. The setting of the balancing means can be decided by calculation as with the adjustable balancing means described above, but the adjustment can also be carried out directly in situ based on a knowledge of the desired flowrate alone.
In practice, it is not enough, in most cases, to regulate each of the balancing means in succession in order to obtain the desired flowrates. This is because distribution networks are often prone to hydraulic interference. This phenomenon makes it necessary to carry out several adjustments on each of the balancing means, utilizing for example a method of successive approximations or carrying out a careful balancing procedure which can only be done properly if a work plan is prepared beforehand and carried out rigorously.
These adjustable balancing means with flowrate measuring device therefore enable the system to be balanced correctly provided the balancing procedure is adhered to rigorously. This method is reasonably complicated to carry out and installers would prefer a much simpler method.
Lastly, there are also flow regulators. Such a regulator, fitted at the head of a branch circuit, keeps the flowrate constant whatever pressure fluctuations are generated in the main circuit by the action of the terminal controls of the emitters served by the other branch circuits. Interference caused by the operation of the other branch circuits of the same system are thereby eliminated.
The use of these flow regulators as balancing means has however a major drawback. If the valves of the emitters served by the circuit equipped with a flow regulator decide to partly close themselves to a greater or lesser degree, thereby necessarily reducing the flowrate, the regulator will attempt to oppose this reduction by opening. The regulator therefore functions as an antagonist to hydraulic disturbances downstream of the regulator. The use of these flow regulators is therefore incompatible with, for example, the thermostatic radiator valves which are currently widely used.
Actually, this type of equipment has no direct relationship with the balancing of systems as defined above. The use of such a flow regulator can be regarded as a palliative to insufficient calculation by replacing a relatively simple static balancing means with a regulating unit containing moving parts, purely in order to avoid the initial regulating operation using one of the procedures indicated above. The use of these flow regulators is limited because, on the one hand, its field of application is restricted owing to incompatibility with thermostatic radiator valves, and on the other hand because it represents a greater investment cost than conventional solutions.
FIGS. 1 and 2 each show a circuit branched off from a heating system equipped with balancing means. In both of these figures, radiators 2 are supplied with heat-transfer fluid via pipes 4. FIG. 1 shows radiators 2 equipped with conventional valves while in FIG. 2 the radiators 2 are equipped with integrated valves. FIGS. 1 and 2 both show a main flow pipe 6 and a main return pipe 8. The branch circuit is connected at a branch point 10 to the main flow pipe 6 and at a branch point 12 to the main return pipe 8. Upstream of the branch point 10 supplying the branch circuit is a balancing valve 14. Downstream of this branch point 10 there is generally an isolating valve 16 which plays no particular part in the balancing of the circuit. At the tail end of each branch circuit is another balancing valve 21. The latter is adjustable and is used to adjust the loss of head of the branch circuit.
In FIG. 1, each radiator 2 is provided upstream of its supply with a thermostatic radiator valve 18 and upstream [sic] with a lockshield valve 20. The thermostatic radiator valve 18 is for thermostatic regulation of the temperature of the room where the radiator 2 is installed, while the lockshield valve 20 is for balancing the system.
In FIG. 2, in the case of radiators 2 with integrated valves, a hydraulic module 22 supplies a radiator 2 and each radiator 2 is fitted with a thermostatic radiator valve 24. As a rule, the housing of the thermostatic radiator valve 24 also contains a lockshield valve. We thus have a hydraulic module 22 allowing heat-transfer fluid to be supplied to the radiator 2, a thermostatic radiator valve for thermostatic regulation, and a lockshield valve (not labeled) alongside the thermostatic radiator valve for balancing the system.
When balancing these circuits (FIGS. 1 and 2) the problems discussed above are encountered.
Document EP-0 677 708 describes the principle of a hot-water heating system comprising several radiators connected together by at least one line. These radiators each have a valve for controlling the flow of fluid through the radiator. In order to ensure favorable conditions of circulation, the valves connected to the radiators are differential pressure control valves equipped preferably with a device for adjusting the set-point value. No concrete embodiment of such a device is disclosed in that document.
It is therefore an object of the present invention to provide an automatic balancing device in order to solve the balancing problems currently encountered with existing balancing means.
To this end, the device proposed is a liquid-based heat-transfer system-balancing device for a heating, air-conditioning or similar system, comprising a first calibrated or adjustable orifice and, situated downstream of the first orifice, a second orifice, wherein the opening of the second orifice is controlled by a poppet valve whose position is controlled by means for moving the poppet valve as a function of the pressure difference between the upstream and downstream sides of the first orifice.
According to the invention, this device is located in two separate bodies connected to each other, a first body corresponding to the first orifice and a second body corresponding to the second orifice.
In a first embodiment, the means for moving the poppet valve as a function of the pressure difference across the first orifice comprise a diaphragm separating a housing into two chambers, one chamber being in communication with the upstream side of the first orifice and the other chamber being in communication with the downstream side of this first orifice. In this form, a compensating spring acting on the diaphragm is advantageously provided.
The balancing device according to the invention preferably also comprises means for bringing about a movement as a function of the temperature of the room in which the device is located, these means acting on the opening and closing of either the first or the second orifice.
The means for bringing about a movement as a function of the temperature of the room in which the device is situated advantageously comprise a thermostatic head of the type used in a thermostatic radiator valve.
In one advantageous embodiment, the means for bringing about a movement as a function of the temperature of the room in which the device is located act on a second poppet valve situated at the first orifice.
In a preferred embodiment, the first body comprises the first orifice, a poppet valve controlling the opening and closing of this orifice, and a thermostatic head acting on the poppet valve, and the second body comprises a diaphragm calibrated if necessary by a spring and integral with a poppet valve which acts on the second orifice formed inside this second body.
In this preferred embodiment, one side of the diaphragm is advantageously connected to the first body via a pipe length or the like and the other side of the diaphragm is advantageously connected to the first body by a radiator.
In the case of a heating circuit with centralized distribution, one side of the diaphragm is for example connected to the first body via a line or the like and the other side of the diaphragm is for example connected to the first body by a radiator and a line.
The present invention also relates to a hydraulic module for supplying heat-transfer fluid to a heat emitter, such as a radiator, and collecting the fluid as it leaves the heat emitter, characterized in that it comprises one of the bodies of a balancing device as described above. Such a module is more especially designed for a radiator with integrated valves. This module takes the flow and return pipes of the heat-transfer fluid, and, via flexible hoses forming a device generally known as a harness, sends the heat-transfer fluid to the radiator inlet and collects the heat-transfer fluid as it leaves the radiator.
In a hydraulic module according to the invention, the balancing device may be situated upstream or downstream of the heat emitter.
The invention also relates to a radiator characterized in that it is equipped with a balancing device according to the invention or with a hydraulic module as described above.
In such a radiator, the automatic balancing device with which it is equipped is situated hydraulically either upstream or downstream of the radiator.